Throughout this document, positional designations such as "front", "across" or the like, are defined as follows. "Front" always points in the direction of shooting. "Lengthwise" always runs parallel to the axis of the bore. "Top" is referenced to a weapon in a normal horizontal firing position.
A blank cartridge device for use with a firearm having a flash reducer is known from U.S. Pat. No. 3,744,370 and has since proven itself. Indeed, blank cartridge devices constructed pursuant to the teachings of the present invention preferably employ the features of the device disclosed in U.S. Pat. No. 3,744,370 pertaining to gas buildup and trapping of shells and particles. Accordingly, U.S. Pat. No. 3,744,370 is hereby incorporated by reference in its entirety.
In addition to U.S. Pat. No. 3,744,370, the following publications relate to blank cartridge devices: U.S. Pat. No. 3,766,822, U.S. Pat. No. 3,732,776 and CH Patent 381,569.
Flash reducers are often attached to known firearms such as automatic weapons via outside threading on the front end of their barrels. A typical known flash reducer consist of a sleeve having inside threading on the rear end by which the flash reducer can be firmly screwed onto the outside threading of an automatic weapon or the like. A cylindrical bore section is connected to the inside threading. The diameter of the inside bore is only slightly larger than the largest diameter of the barrel bore. The purpose of this cylindrical bore section to the protect the muzzle of the barrel from damage, which could otherwise result, for example, from improper cleaning. A nozzle-like bore section that enlarges toward the front end of the flash reducer is connected to the cylindrical section. The side wall of the nozzle section is perforated by radial openings that are generally designed as longitudinal slits. The front peripheral edge of the nozzle section has two notches opposite each other in the transverse direction. A screwdriver-like tool can be attached to these notches in order to either screw the flash reducer onto the barrel or to unscrew it from the barrel. The flash reducer can also have flattenings on its outside for attachment of a screwdriver.
As mentioned above, blank cartridge devices are known in the art. One such known blank cartridge device has an essentially cylindrical block with a central blind hole into which a sleeve is inserted. The blind hole is open to the rear and has an inside diameter which is much smaller than that of the barrel. The block has at least one spiral groove on the front part of its outside periphery. This spiral groove is connected to the blind hole by at least one transverse hole. The block is welded into a bushing, so that the spiral groove is covered from the outside.
If a blank cartridge is fired by a firearm with the above described blank cartridge device mounted, the propellant gases that form are forced to flow through the sleeve, into the blind hole, and then, through the covered, narrow spiral groove. This forcing of the propellant gases through the spiral groove significantly increases the pressure in the barrel, thereby causing the gas pressure or recoil pulse required to reload the firearm to build up within the firearm. Any foreign objects that are released when the blank cartridge is fired (for example, splinters of a wooden projectile or particles of a burst plastic cartridge), and which reach the spiral groove, are placed into eddy-like motion by the spiral groove such that, after leaving the spiral groove, they are carried outward, reduced in size, with a high centrifugal force component and are trapped by the forward protruding bushing.
If, on the other hand, a live cartridge is inadvertently loaded into the firearm, it will be braked in the sleeve and, if necessary, trapped by the bottom of the blind hole. In such a case, the propellant gases are relieved through the spiral groove. The barrel withstands the briefly developed overpressure undamaged, as does the mount on the muzzle. Only the blank cartridge device is damaged, and it must be replaced.
Unexpected problems develop in the above-described blank cartridge device. For example, in order to use the above-described blank cartridge device, the flash reducer must be removed from the firearm and the blank cartridge device mounted in its place. In order for the flash reducer not to loosen despite firing, its inside threading must be forcefully tightened onto the outside threading of the barrel. To unscrew the flash reducer before use of the blank cartridge device and to subsequently screw it back on, tools of the aforementioned type are furnished to the armorer of the troops who issues the firearm. In practice, the armorer will typically not pass along these tools to the troops in order to save themselves the effort of administrative work in case of loss.
At any rate, before each new weapon is issued, its flash reducer is typically loosened and only slightly tightened by hand.
In the case of a fixed flash reducer, the troops will sometimes loosen the flash reducer by inserting a bayonet or another available tool through the radial slit in the side wall of the flash reducer. Such an approach runs the risk of damaging the flash reducer. Moreover, loosely screwed-on flash reducers significantly influence shooting accuracy and can also be lost. This problem can be eliminated by a corresponding regulation, which, for example, assigns an inspector to bring along tools of the mentioned type and to ensure their proper use when weapons are issued and returned before and after use of blank cartridge devices.
Some of these problems are partially solved by the blank cartridge device disclosed in U.S. Pat. No. 3,744,370. That blank cartridge device can be pushed over the flash reducer and attached to either the barrel or the flash reducer. Therefore, when the blank cartridge device is mounted, the flash reducer remains in its position on the barrel. As a result, the flash reducer does not need to be removed by the troops during normal use of the weapons. The blank cartridge device is mounted and removed from the weapon as needed.
Advantages are gained by this approach. For example, because the flash reducer need never be removed from the barrel, it permanently protects the muzzle. In addition, because the flash reducer can remain on the muzzle at all times, the flash reducer can optionally be screwed on or shrunken on by heat, so that it cannot be loosened by simple means. It is even possible to weld the flash reducer to the barrel or to produce the flash reducer in one piece with the barrel. The most favorable procedure can, therefore, be chosen for the flash reducer and its attachment, since it no longer has to be unscrewed by the troops.